lesson 7 PSG Instrumentation Signal Derivation Questions and Answers 2024

lesson 7 PSG Instrumentation Signal Derivation Questions and Answers 2024 The way we record specific sleep variables is by choosing ____ signals (from electrodes or other devices) and passing them through a _______ ______ two differential amplifier A differential amplifier is designed to ... measure and record the differences in voltage between two incoming signals. The selection of the two signal sources is called a _______. derivation In analog PSG systems, a derivation is chosen by selecting the dials on the _______ _______ ______ corresponding to the desired electrode or sensor leads plugged into the ______ _______. The derived signals are then forwarded to the ______ _____ of their respective ________. electrode selector panel electrode jackbox input terminals amplifier the signal route of bio-electrical potentials from patient to pens in analog PSG's includes the signal traveling from the patient to the electrode _____, then the electrode _______ ______, to the _______ ______, and the output signals are sent to writing instruments called _________ or _________. jackbox selector panel differential amplifier galvanometers oscillographs Each amplifier has two input terminals, identified as ___ and ___. G1 G2 The terminals, G1 and G2, represent the two _____ for a selected _________. The letter "G" stands for _____ or _____. inputs derivation grid gate In polysomnography, the setup typically has G1 receiving signals from a _______ ______, and G2 is used to receive signals from a ________ _______. exploring electrode reference electrode to route an EEG derivation of C3/M2 from the electrode selector panel to an amplifier, the PSG technologist would select C3 among the row of pushbuttons corresponding to ___, and M2 among the row of pushbuttons corresponding to ____. G1 G2 Common mode rejection is the method by which a ... differential amplifier rejects similar voltages and amplifies different voltages. In CMRR, if an identical voltage comes through the C3 electrode and M2 electrode at the same time, it will be _______ by the amplifier and there will be no ____ _______ on the polygraph chart. However, if one electrode picks up a signal that is stronger than the other, or of opposite ________, then the ______ between the two will be recorded. rejected pen deflection polarity difference Bio-electrical potentials received from your patient can, at any given time, be described as having a positive or a negative electrical orientation in relation to _______ (______ volts). This electrical orientation is called ________. ground zero polarity As the voltages of two incoming signals are compared by a _______ _______, the resulting output to the polygraph pen may either be _______ or _______. differential amplifier positive negative By international agreement, EEG instruments and polysomnographs are configured so that if a signal received through input terminal 1 or G1 is more negative than a signal received through input terminal 2 or G2, there will be an ______ pen deflection on the chart. So a ______ pen deflection would result from a signal received through G1 being more positive than a signal received through G2. upward downward The recorded voltage differences between the two input signals are equivalent to subtracting input ___ from input ___. G2 G1 For example, if input G1 receives -100 uV and input G2 receives -50 uV, the output to the pen will be ____ uV. -50 If output to the pen is -50uV and an amplifier is calibrated to a sensitivity of 50 uV per centimeter, the pen will move upward ___ centimeter. 1 If input G1 receives +50 uV and input G2 receives -25 uV, the output will equal ___ uV, with a sensitivity of 50uV per cm, the pen will deflect downward ____ centimeters. +75 1.5 derivation where signals from an exploring electrode are compared to signals from a reference electrode. referential derivation any electrode used to obtain a signal from a specific region of the scalp, face, or body. exploring electrode 6 Examples of EEG exploring electrodes F3, F4, C3, C4, O1, and O2 Other examples of exploring electrodes include electrodes used for detecting ____ movements and _____ muscle activity. eye chin electrode is one that is purposely placed in an area that is relatively inactive, when compared to the exploring electrode. reference electrode Reference electrodes provide a way to help ______ the signals received from an exploring electrode. isolate In polysomnography, ________derivations are used to record EEG and eye movements. referential